In general, the washing machine or a dryer is used for washing or drying laundry.
In the washing machines, there are pulsator type washing machines which washes laundry with water circulation generated as a disk shaped pulsator is rotated, and drum type washing machine which washes laundry by using head and friction of washing water and the laundry generated in a horizontal tub as the tub is rotated.
Recently, even a laundry machine is developed, in which steam is sprayed to wash or dry cleaning the laundry.
Of the various laundry machines, a drum type washing machine having the steam, generator will be described, as an example.
Referring to FIG. 1, a related art washing machine having a steam generator is provided with a cabinet 10 of an exterior of the washing machine, a cylindrical tub 20 horizontally supported in the cabinet 10 for holding washing water, a drum 30 rotatably mounted in the tub 20, a driving motor (not shown) for driving the drum 30, and a steam generator 50 for supplying steam to the drum 30.
The cabinet 10 has a laundry opening 13 in a front in communication pith an inside of the drum 30 for putting in/taking cut laundry, and a door 11 mounted so as to be rotatable in a front direction for opening/closing the laundry opening 13.
In the meantime, at one side of the drum type washing machine, there are a water supply valve 15 and a water supply hose 25 connected to an external water pipe (not shown) for supplying washing water to the tub 20.
The steam generator 50 is connected to the water supply hose 25 for introducing water thereto, and heats the water to generate steam to supply to the drum 30.
The steam generator 50 also has a steam supply pipe 53 at one side for guiding and spraying the steam generated at the steam generator 50 into the drum 30.
It is preferable that the steam supply pipe 53 has an end portion having a nozzle shape for smooth spray of steam into the drum 30, and it is preferable that the end portion is exposed to an inside of the drum 30 for discharging the steam thereto.
In the meantime, in order to prevent the steam sprayed into the inside of the drum 30 from making direct contact with the laundry, it is preferable that the steam supply pipe 53 is connected to one side of an upper side of the drum 30.
The steam generator 50 will be described in more detail Math reference to FIGS. 2 and 3.
Referring to FIG. 2, the steam generator 50 is provided with a lower housing 81 for forming an exterior and a space for holding water, an upper housing 82 coupled to an upper side of the lower housing 81, and a heater 55 for heating water held in the steam generator 50.
The upper housing 82 has a water inlet 52a at one side connected to the water supply valve for introduction of water into the steam generator 50, and an outlet 52b at the other side connected to a steam supply pipe 53 for supplying the steam generated thus to the drum 20.
Referring to FIG. 3, the heater 55 is mounted to a lower side of the upper housing 82, for heating the water submerged in the water completely once the water is introduced to the steam generator 50.
Mounted on one side of the upper housing 82, there are the water level sensor 60 for sensing the water level of the water therein, and a temperature sensor 57 for measuring temperatures of the water and steam heated by the heater 55.
The temperature sensor 57 also measures the temperature of the steam generated at the steam generator 50, and cuts off power to the heater 55 if the temperature is higher than a reference temperature, to prevent the heater 55 form overheating.
The water level sensor 60 measures the water level of the water in the steam generator 50, to maintain an appropriate level of water.
That is, if the water level of the water in the steam generator 50 is lower than the reference value, the water supply valve 15 is opened, to supplement the water, and, if the water level of the water in the steam generator 50 is higher than the reference value, the water supply valve 15 is closed, to stop the water supply, and put the heater 55 into operation to generate the steam.
In the meantime, the related art water level sensor 60 is provided with a receptacle housing 61 which is an exterior thereof and used for securing the related art water level sensor 60 to the steam generator 50, and electrodes 62, 63, and 64 extended downward to a lower side of the receptacle housing 61, for sensing the water level of the water in the steam generator 50.
The electrodes 62, 63, and 64 are mounted at appropriate heights from a bottom of the upper housing 82 for sensing the water level of the water in the steam generator 50.
However, the steam generator of the drum type washing machine has the following problems.
First, the water level sensors sense the Water level as the water connects electrodes of different lengths depending en the water level.
If the water boils heated by the heater to form bubbles, and is splashed to the water level sensor in a course the bubbles are formed and burst, the water formed between the electrodes serves to connect the electrodes of the water level sensor as the formation and bursting of the bubbles keeps taking place. According to this, the water level sensor mistakes in sensing the height of the water, to cause malfunction of the water level sensor.
Second, foreign matters introduced into the steam generator mixed with the water affects the water level sensor in the steam generator if the foreign matters deposit on the water level sensor.
That is, the foreign matters introduced into the steam generator from an outside thereof deposit on the water level sensor, to impair sensitivity and a mechanical lifetime of the water level sensor.